1. Field of the Invention
This invention relates to digital records of audio performances and to player apparatus for reproducing the sound performances from the records, and to a method and apparatus for generating audio warning signals prior to the start of reproduction of each performance.
2. Prior Art
If the volume control of a phonograph is set too high before the reproduction of the recorded musical performance begins, the listener may be subjected to an uncomfortably high level of sound when the performance starts. If earphones are used, these sounds can damage the listeners eardrums. When a conventional phonograph record is played, the background noise generated by the record at the leading edge, prior to the start of the performance, generates a warning signal to the listener so that an excessively high setting of the volume control can be detected before the performance starts and the volume control can be lowered to a more appropriate level.
This background noise level produces a hiss on reproduction throughout the performance. Removal of this background noise level is one of the advantages provided by systems which record the sound performance in digital form, usually on record media consisting of laser readable disks or magnetic tape, and employ a digital player to reproduce the performance stored on the record media. The absence of random background noise during the reproduction of the performance is an unalloyed benefit, substantially improving the quality of the reproduction, and the silence due to the absence of background hiss before the reproduction of the first recorded sound performance on the media and between sequential performances on the same record, conveys to the listener an impression of the high quality of the reproduction process.
But that very silence creates a problem with prior art digital record players for those recordings, in that the listener receives no audible signal as to the setting of the volume control of the player, and if the volume control is set too high, the actual musical performance may begin with an unpleasant or even dangerous blast of sound. The danger is particularly acute if the listener is using earphones and can result in temporary or even permanent loss of hearing.